Booms used in lifting and/or digging have typically become more massive in recent years, but not necessarily more efficient or better performing. For example, it has become an industry standard to provide backhoes with the capability of digging to a depth of fourteen feet. In achieving that capability, many units have become so massive that they likewise require massive prime movers in order to provide counterbalance during roading or movement to varying locations at the job site. Inasmuch as the backhoes are typically attached to the rear ends of such prime movers at a location substantially rearwardly of the rear wheels thereof, a natural situation arises in which the rear wheels serve as a fulcrum point and the attached backhoe tends to rock the prime mover backwards unless sufficiently counterbalanced by structure at the front end of the prime mover.
This condition is aggravated in many backhoes by the fact that even when fully raised and folded for transport, the center of gravity of such units is well behind the vertical swiveling axis of the backhoe because the boom thereof extends upwardly and rearwardly from the prime mover.
Attempts have been made to alleviate this situation such as in Long et al. U.S. Pat. No. 3,376,984 in which the backhoe, when folded, has its boom disposed beyond vertical and leaning forwardly toward the prime mover so as to dispose the center of gravity of the backhoe closer to the fulcrum point presented by the rear ground wheels. The arrangement in said Patent, however, requires the hydraulic lift cylinders for the boom to reverse their strokes as the boom swings beyond vertical, a condition that is not only awkward to obtain but which also requires that the boom be slammed abruptly into its home position in order to have sufficient inertia to carry the same past vertical.
Furthermore, such an arrangement does nothing to alleviate the great bulk of the backhoe necessary to obtain the desired fourteen-foot digging depth. Hence, even when folded, the backhoe constructed according to said U.S. Pat. No. 3,376,984 presents a relatively high silhouette caused by excessive boom length, and the massive nature of the unit necessitates more powerful, massive prime movers to operate the same, all of which quite naturally results in greater fuel consumption, higher material costs and even larger trailering equipment in order to transport the unit from one job site to another over the road.